The present application generally relates to internal combustion engine diesel exhaust systems, and more particularly, but not exclusively, to low temperature dosing of reductant in diesel exhaust systems.
Modern systems that include internal combustion engines often include a selective catalytic reduction (SCR) exhaust aftertreatment system to control exhaust system emissions. SCR systems typically include a reductant storage tank connected to a doser that injects reductant into the exhaust stream to reduce NOx emissions. Under normal operating conditions, reductant is injected into the exhaust stream at a continuous rate.
Under low temperature operating conditions, injecting reductant at a continuous rate causes reductant buildup and reductant slip. Further, not injecting reductant at low operating conditions causes NOx emissions to exceed required limitations on NOx emissions. Therefore, a need remains for further improvements in systems, apparatus, and methods for performing dosing of a reductant in exhaust aftertreatment systems at low temperature operating conditions.